A review of cytological specimens from horses with and without clinical signs of respiratory disease.

Thirty-six transtracheal washing (TTW) and 12 bronchoalveolar lavage (BAL) specimens collected in clinical practice from horses with and without respiratory disease were reviewed. Cytological features were considered in accordance with the presenting complaint, clinical signs, clinical diagnoses, microbiological, radiographic and/or endoscopic findings, therapy, and response to therapy. The trichrome-stained TTW and BAL specimens were useful in interpreting the results of concurrent microbiological cultures, and determining whether a condition was present based on occurrence of typical cytological features of patterns (e.g. probable allergy, chronic obstruction, uncomplicated exercise-induced pulmonary haemorrhage), determining pathological/anatomical diagnoses (e.g. bronchitis, bronchiolitis and/or alveolitis; presence of metaplasia or dysplasia) and possible aetiologies (e.g. allergy, bacterial infection). Review of these cases confirmed the practicality of using cytological specimens to evaluate the equine respiratory tract; there were few unsatisfactory specimens and no reported complications. The importance of cytological evaluation of the equine respiratory system was emphasised by the identification of 13 cases in which clinical signs were not apparent at physical examination. Sequential collections of cytological specimens from foals, young horses before and during early training, and mature horses in training may provide more information about the response of the equine lung to stresses associated with training and/or common environmental exposures.

Use of esophagoscopy in the diagnosis of esophageal squamous cell carcinoma in a horse.

Esophagoscopy allowed visualization and biopsy of a lesion within a diverticulum of the esophagus in an adult horse. Although the biopsy specimen obtained was small, diagnosis of squamous cell carcinoma was possible from histologic examination of the esophageal tissue sample retrieved by use of endoscopy.

Variation in glycogen and mucins in the equine uterus related to physiologic and pathologic conditions.

Histochemical stains were applied to six equine uterine biopsies representative of the physiologic breeding season, Spring and Fall transition, and Winter anestrus periods. These were compared with uterine biopsies from six mares with intrauterine urine pooling, eight mares used to study the uterine response to indwelling catheterization, and necropsy specimens from four pregnant mares at approximately 60 or 100 d of gestation. Alcian blue staining at pH 2.5 or 1.0 was used to identify the presence of carboxylated and sulfated acid mucins or only suflated acid mucins, respectively. Periodic acid-Schiff staining was used to identify neutral mucosubstances or glycogen, with or without prior diastase digestion. The uterine glands contained glycogen, which was most abundant during the physiologic breeding season. The luminal epithelial cells during the physiologic breeding season and Spring and Fall transition contained predominately carboxylated acid mucins. Carboxylated acid mucin secretion also was stimulated by indwelling catheterization and intrauterine urine pooling. It is hypothesized that secretion of carboxylated acid mucins by the endometrial epithelium may be elicited by hormonal or irritative/inflammatory stimuli, and it may be a protective response.

"Repair cells" in equine uterine cytologic and histologic specimens.

Cells resembling those known as "repair cells" in gynecologic cytology specimens from women were identified in uterine cytology specimens from infertile mares treated with antibiotics using indwelling uterine catheters. This prompted a study of the effect on the equine uterus of indwelling catheterization without antibiotic infusion, using light microscopic examination of cytologic and biopsy specimens and electron microscopic examination of biopsy specimens. Cytologic and biopsy specimens had features within normal limits at the start of the study. Following five days of indwelling catheterization, neutrophils were present in both cytologic and biopsy specimens. In cytologic specimens, numerous groups of "repair cells" were present; similar cells in biopsy specimens indicated this was a focal reaction. The large nuclei and prominent nucleoli of the "repair cells" suggested cellular proliferation or regeneration. However, this was contradicted by the ultrastructural sparsity of ribosomes, endoplasmic reticulum, Golgi apparatus and mitochondria. Inflammation and "repair cells" were not present in cytologic or biopsy specimens collected 40 days after the start of the study. Although these cells may be a component of a repair process, our results support the hypothesis that "repair cells" in human and equine gynecologic cytology specimens are injured, rather than regenerating, cells. The term dysphaneroplastic (Greek: "abnormal cytosol development") is proposed to describe these cells since the cytoplasm does not reflect the features of cellular activity suggested by the nuclear appearance.

Equine endometrial cytology.

The simplicity of collection of material for cytologic preparations belies the complexity of smear interpretation beyond recognition of neutrophils. Knowledge concerning cancer cytology moves rapidly, for cancer is a progressive, often fatal disease so that tissue for comparison and confirmation of interpretation often becomes available. This is not true for cytologic study of the equine endometrium. Lesions detected by means of cytology smears may be transient and regress, offering little information concerning their etiology or consequences. They may be focal and missed in the corresponding biopsy. Such experiences should lead to the abandonment of equine endometrial cytology, but have only strengthened our interest and enthusiasm for this technique in the study of the uterus. We have found it to be useful in a limited number of clinical circumstances in which other techniques have failed. This, plus the growing number of supportive clinicians using cytopathology service and the large number of mares with fertility problems, leads us to believe that further investigation of equine endometrial cytology may prove to be even more helpful as a clinical tool.

Inclusions in equine cytologic specimens.

Inclusions and cellular changes were seen in cytologic specimens from 1 healthy horse, 6 horses hospitalized because of respiratory problems, and 1 horse hospitalized because of colic and hepatitis. Two bronchial aspirates contained detached ciliated cytoplasmic tufts and cytoplasmic inclusions characteristic of the specific degenerative process called ciliocytophthoria. These changes and inclusions resembled those seen in bronchial aspirates from human beings with parainfluenza virus infection. Four bronchial aspirates and 2 serous fluid specimens had nuclear inclusions resembling those seen in a variety of specimens from human beings with herpetic infections. The abnormalities and inclusions were similar to changes seen in cell monolayer and suspension cultures infected with equine herpesvirus type 1.

Feline bronchial cytology: histologic/cytologic correlation in 22 cats.

Trichrome-stained bronchial washings were obtained from 22 cats at necropsy and compared to lung tissue sections obtained at the same time. In three of the 22 cats, antemortem bronchial washings also were obtained. Sixteen of the cats were clinically ill and six were clinically normal and served as controls. On the basis of comparison of histologic sections and bronchial washings, patterns were detected in the washings indicative of general processes such as alveolar edema, chronic passive congestion, mucous metaplasia, and inflammation. Two specific etiologic agents, Histoplasma capsulatum and Toxoplasma gondii, each were seen in one washing.

Eosinophils in equine uterine cytology and histology specimens.

In a review of specimens from 80 mares with concurrently collected endometrial biopsy and cytology preparations, eosinophils were found in 33 specimens from 27 mares. In 22 of 27 mares, there were conditions predisposing to pneumovagina, which presumably led to pneumouterus. Thirty-two of the 80 mares also had conditions predisposing to pneumovagina but no eosinophils in the uterine specimens. Experimental introduction of air into the uterus of 3 mares resulted in eosinophils in their uterine specimens.

The influence of dietary fat and non-specific immunotherapy on carcinogen-induced rat mammary adenocarcinoma.

The incidence of mammary adenocarcinoma in Sprague-Dawley female rats, caused by the carcinogen 7,12-dimethylbenz(alpha)anthracene, was influenced by the level of dietary fat fed after exposure to carcinogen. Carcinogen was given by stomach tube to 50-day-old rats, and tumors were evaluated when rats were 9 months old. Rats on diets containing 20% unsaturated fat had a tumor incidence of 97%, while rats changed to a low-fat diet (2% unsaturated fat) three or four weeks after exposure to the carcinogen had an incidence of 45%. Some rats on each diet were given two treatments with the methanol extraction residue of Bacillus Calmette-Guerin, either three and five weeks after carcinogen or four and six weeks after carcinogen. Tumor incidence in the treated group and the untreated group was the same when rats were maintained on the high-fat diet, but tumors in the treated group were larger and the disease was more severe by histological criteria. These tumors were more anaplastic and many were extensively infiltrated with lymphocytes compared to the untreated group. Tumor incidence was significantly lower in rats changed to the low-fat diet (45%) than in those on the high-fat diet (97%), and tumor incidence was reduced to 20% when rats changed to the low-fat diet were treated with methanol extraction residue. The treated group had less severe disease than the untreated group on the low-fat diet. Only half the tumor-bearing rats in this group had malignant tumors, and none were invasive. Methanol extraction residue protected most rats on the low-fat diet against mammary adenocarcinoma, and reduced the severity of disease in those rats that did develop tumors. Methanol extraction residue treatment provided no protection, and even increased the severity of disease, in rats on the high-fat diet.

Frequency of canine and feline tumors in a defined population.

The Tulsa Registry of Canine and Feline Neoplasms was the second animal tumor registry in the United States concerned with a defined population in a delimited geographic area. Only tumors histologically confirmed by registry pathologists were included in frequency statistics based on the annual dog and cat population presented to veterinarians. During the first registry year, about 1% of the 63,504 dogs and 0.5% of the 11,909 cats had one or more primary tumors. While the incidence rate for malignant tumors in dogs was similar to that in cats, the incidence of benign tumors of dogs was over 10 times that of cats. The most common tumors were sebaceous adenoma in dogs and lymphosarcoma in cats. Mammary cancer was the most common malignant tumor in dogs. Mammary tumors of female dogs were significantly more frequent in Pointers, Poodles and Boston Terriers, in that order, than in other breeds. A greater incidence of mammary tumors among intact compared to spayed female dogs was seen for virtually every age group except in the Pointer breed.

Use of cytology for tumor diagnosis in private veterinary practice.

Cytologic and histologic services were offered without charge to veterinarians in the greater Tulsa area by the Tulsa Registry of Canine and Feline Neoplasms. During the first 3 years of operation, all veterinarians treating dogs or cats used the histologic service and slightly less than one-half used the cytologic service. The number of cytologic accessions increased 77% during the 2nd year and 27% during the 3rd year. For corresponding years, the increase in histologic accessions was 5% and 11%. The 7 hospitals from which 79% to 90% of the cytologic specimens were received were compared with the 8 to 14 hospitals that used cytologic service infrequently. The frequency of use of cytology was not related to number of veterinarians in the hospital, number of animals seen in the hospital, or number of tissues received by the Registry from the hospital. The order of frequency of the most numerous cytologic specimens was fine-needle aspirations of masses in or beneath the skin, mammary preparations, effusion sediments, fine-needle aspirations from lymph nodes, and urine sediments.